KCTD1 suppresses canonical Wnt signaling pathway by enhancing β-catenin degradation

• Published in: PloS one Vol. 9; no. 4; p. e94343
• Main Authors: Li, Xinxin, Chen, Cheng, Wang, Fangmei, Huang, Wenhuan, Liang, Zhongheng, Xiao, Yuzhong, Wei, Ke, Wan, Zhenxing, Hu, Xiang, Xiang, Shuanglin, Ding, Xiaofeng, Zhang, Jian
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15-04-2014; Public Library of Science (PLoS)
• Subjects: Aberration; Adenomatous polyposis coli; Adenomatous Polyposis Coli Protein - metabolism; Amino Acid Sequence; beta Catenin - metabolism; beta-Transducin Repeat-Containing Proteins - metabolism; Biology; Biology and Life Sciences; Carcinogenesis; Carcinogens; Casein; Casein kinase I; Casein Kinase I - metabolism; Cell division; Co-Repressor Proteins; Colorectal cancer; Degradation; Down-Regulation; Education; Embryogenesis; Embryonic growth stage; Gene expression; Genes, Reporter - genetics; Glycogen; Glycogen synthase kinase 3; Glycogen Synthase Kinase 3 - metabolism; Glycogen Synthase Kinase 3 beta; HEK293 Cells; HeLa Cells; Humans; Immunofluorescence; Immunoprecipitation; Inhibitors; Laboratories; LEF protein; Life sciences; Ligands; Molecular Sequence Data; Mutation; p53 Protein; Phosphorylation; Plasmids - genetics; Potassium; Proteasome Endopeptidase Complex - metabolism; Proteasomes; Proteins; Proteolysis; Repressor Proteins - chemistry; Repressor Proteins - metabolism; Research and Analysis Methods; Signal transduction; Signaling; Stability; Transcription factors; Transcription, Genetic; Transducin; Tumor suppressor genes; Tumor Suppressor Protein p53 - metabolism; Ubiquitin; Ubiquitin-protein ligase; Ubiquitination; Wnt protein; Wnt Signaling Pathway; β-Catenin; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0094343

The canonical Wnt signaling pathway controls normal embryonic development, cellular proliferation and growth, and its aberrant activity results in human carcinogenesis. The core component in regulation of this pathway is β-catenin, but molecular regulation mechanisms of β-catenin stability are not completely known. Here, our recent studies have shown that KCTD1 strongly inhibits TCF/LEF reporter activity. Moreover, KCTD1 interacted with β-catenin both in vivo by co-immunoprecipitation as well as in vitro through GST pull-down assays. We further mapped the interaction regions to the 1-9 armadillo repeats of β-catenin and the BTB domain of KCTD1, especially Position Ala-30 and His-33. Immunofluorescence analysis indicated that KCTD1 promotes the cytoplasmic accumulation of β-catenin. Furthermore, protein stability assays revealed that KCTD1 enhances the ubiquitination/degradation of β-catenin in a concentration-dependent manner in HeLa cells. And the degradation of β-catenin mediated by KCTD1 was alleviated by the proteasome inhibitor, MG132. In addition, KCTD1-mediated β-catenin degradation was dependent on casein kinase 1 (CK1)- and glycogen synthase kinase-3β (GSK-3β)-mediated phosphorylation and enhanced by the E3 ubiquitin ligase β-transducin repeat-containing protein (β-TrCP). Moreover, KCTD1 suppressed the expression of endogenous Wnt downstream genes and transcription factor AP-2α. Finally, we found that Wnt pathway member APC and tumor suppressor p53 influence KCTD1-mediated downregulation of β-catenin. These results suggest that KCTD1 functions as a novel inhibitor of Wnt signaling pathway.